1. Field of the Invention
The present invention relates generally to the field of take-up frames and similar structures for maintaining desired force or alignment of rotating machinery. In particular, the invention relates to a system for providing feedback of forces exerted on a bearing set in a take-up frame, permitting a system or operator to regulate the force at the desired level.
2. Description of the Related Art
In rotating equipment, bearing assemblies are traditionally provided for securing a rotating element, typically a shaft, with respect to support or stationary components. By way of example, in conveyer belts, chain drives, and similar systems, active or passive shafts are supported on anti-friction bearing assemblies for free rotation with a conveyor belt, chain assembly, or other transmission component. To maintain proper tension in these components, one end of the component is typically fixed in space such as on a driven pulley, while the opposite end is movable. The fixed end may be support on a pillow block or flanged bearing assembly, while structures such as take-up frames are employed at the movable end to provide for adjustment in tension of the transmission component.
Take-up frames include a framework supporting a movable bearing set. The framework may include glides, guiding rails, or similar confinement and alignment members which contact the bearing set to support it rigidly, while allowing its displacement within the frame. Special bearing sets may be employed, including housings adapted to receive a tension or compression adjustment member, such as a threaded rod, such as an acme type screw or the like. The threaded rod is, in turn, supported in the take-up frame, typically via a threaded nut. Adjustment in the position of the bearing assembly is made by turning the threaded rod or the nut to slide the bearing set into the desired location.
Take-up frames and bearing sets of the type described above are typically employed to maintain tensile or compressive forces within machine systems. Upon installation, the take-up frames are situated generally parallel to the forces to be regulated, such that adjustment of the bearing set position will tend to tighten or relax a machine component fitted around the associated rotated member. For belt conveyors and the like, take-up frames are often positioned on either side of an active or passive pulley. In other systems, such as chain drives, similar take-up frames may be positioned on one or both sides of an endless chain. Other applications exist in which compressive or tensile forces are maintained in more static (non-continuous or non-rotating) equipment. In such applications also, the take-up frame will be placed under compressive or tensile forces depending upon the orientation of the regulating element with respect to the forces applied.
Several drawbacks exist in conventional take-up frame structures. For example, forces exerted on take-up frames have commonly been judged by operator "feel," potentially leading to substantial variation in the actual forces applied to the systems, depending upon the operator experience and judgment. While certain operators may accurately judge loads during steady state operation, even these operators may fail to take into account excessive loading which can result during intermittent phases of operation. Where an inexperienced operator places too little load on the system, slack can occur, leading to accelerated component wear and eventual failure. Where excessive loading is placed on the structure, excessive heating can occur in the bearing, leading to its premature failure. Moreover, in systems employing take-up frames on either side of a rotating member, such as in conveyer systems, inconsistent loading on either side of the rotating component can lead to misalignment and tracking problems, as well as to uneven and excessive loading and failure of both the conveyer belt and the bearings. In summary, non-uniform or excessive loading of take-up frame supported systems may result in excessive bearing heating, pulley shaft deflection, bushing fatigue, and belt carcass damage, all potentially leading to costly downtime and maintenance.
There is a need, therefore, for an improved system for regulating loading of bearing sets in take-up frames. There is a particular need for a technique which can be used in connection with conventional take-up frame structures, permitting feedback of both tensile and compressive forces exerted on bearing sets by regulation of the take-up frame adjustment members.